Nanoscale zero valent iron-activated persulfate coupled with Fenton oxidation process for typical pharmaceuticals and personal care products degradation

Abstract

In this study, a two-staged nanoscale zero valent iron-activated persulfate coupled with Fenton (nZVI-PS-Fenton) oxidation process is applied to remove typical pharmaceuticals and personal care products (PPCPs) from water. Due to the partial substitution of PS by cheaper H2O2, the main advantage of the combined treatment is to reduce the cost of oxidation reagent and reduce sulfate release in water. Experiment results indicated that sulfamethazine (50 mg L−1) is degraded up to 96% within 30 min using 2 mM nZVI, 1 mM PS and 0.5 mM H2O2. Thanks to the acidifying effect of persulfate addition for degradation of PPCPs and reduction of pH value in the first stage, the Fenton reaction could further finalize sulfamethazine degradation independently from initial pH. The degradation of PPCPs obeyed pseudo-first-order reaction kinetics. The effect of organic and inorganic radical scavengers naturally present in water was studied: results indicated that they actually have an inhibition effect, but this is perceivable at rather high concentrations. Nine typical PPCPs (i.e., bisphenol A, indomethacin, norfloxacin, tetracycline, paracetamol, carbamazepine, phenacetin, sulfamethoxazole and sulfamethazine) were significantly degraded (77–100%), suggesting that the proposed nZVI-PS-Fenton process can be applied to remove such kind of pollutants from (waste) water streams and prevent their spread into the environment.